Image pickup apparatus

ABSTRACT

An image pickup apparatus comprising a first lens unit which comprises at least a negative lens element and at least a positive lens element and has negative refractive power, a second lens unit which has positive refractive power, and an optical path bending reflecting optical element which has a variable reflecting surface disposed in an airspace between a most object side lens component of the first lens unit and a most object side lens component of the second lens unit. This image pickup apparatus changes a magnification by moving the second lens unit along an optical axis and corrects a deviation of an image location by varying a shape of the variable reflecting surface of the reflecting optical element.

BACKGROUND OF THE INVENTION

[0001] a) Field of the Invention

[0002] The present invention relates to an improvement in an opticalsystem which is included in a photographic system, a view finder system,automatic exposure control system, an automatic focusing auxiliary lightillumination system or the like for an image pickup apparatus such as afilm camera, a digital camera, a video camera or the like.

[0003] b) Description of the Prior Art

[0004] Demands for thinner configurations of image pickup apparatusessuch as film cameras, digital cameras, video cameras and the like becomehigher and higher year by year. It is therefore important to shortentotal lengths of optical systems such as photographic optical systemsand view finder optical systems to be used in the image pickupapparatuses.

[0005] Since there lies a limit in shortening a total length of such anoptical system by reducing a number of compositional lens elements, itis attempted to shorten a total length by bending an optical systemusing a mirror.

[0006] For bending an optical system, however, it is necessary toreserve a space for a bent portion, and a space for moving lens units ina zoom optical system or moving lens unit(s) for focusing in particularis apt to be insufficient, thereby making it difficult to obtain arequired zoom ratio and shorten an extremely short distance. In case ofa view finder, it is difficult to shorten a total length since a spacemust be reserved for moving a lens unit to adjust or correct diopter.

[0007] Furthermore, it is desirable for automatic exposure control of animage pickup apparatus to make variable a weighted coefficientdistribution for the so-called weighted mean light measurement accordingto a program of what portion of a photographing range of an object is tobe considered at what ratio. There are adopted, for example, a centerweighted mean light measurement, spot light measurement and the like.For carrying out such a variable weighted mean light measurement, it iseffective to change a focus point location of a condenser lens componentwhich condenses rays on a sensor. In such a case, it is necessary to usea mechanism which changes a relative positional relation between thecondenser lens component and the sensor, thereby complicating an imagepickup apparatus.

[0008] On the other hand, zoom lens systems nowadays constitute a maincurrent of photographic optical systems for image pickup apparatuses andwhen an exclusive condenser optical system has a single focal point, alight measuring area is changed relative to a photographing range of anobject by zooming, whereby the center weighted mean light measurement ata wide position may be a mean light measurement at a tele position. Insuch a case, a condenser lens component which condenses rays on a sensorin a light measuring system must have a vari-focal function. When thecondenser lens has the vari-focal function, however, a magnificationchanging mechanism of the light measuring system is complicated and whenthe condenser lens component is interlocked with a zoom lens system of aphotographic system, the mechanism is more complicated.

[0009] Digital cameras (electronic cameras) have recently beenattracting attention as cameras of a next generation which are tosubstitute for silver salt 35 mm film cameras (Leica camera by popularname).

[0010] An effective image pickup surface of an image pickup devicegenerally used for a digital camera has a size which is much smallerthan that of a silver salt film. Therefore, the image pickup device hasdefect that it has too large a depth of field can hardly provide aneffect of defocus. In contrast, there is a case where pan-focus isdesired.

[0011] In order to realize these effects, there is conceivable a methodto carry out an image processing so as to change an apparent depth offield by composing image data of an identical scene having focus pointswhich are different little by little. In such a case, however, it isnecessary to obtain a plurality of image data in a short time and at ahigh speed while changing a focus point.

[0012] It is therefore necessary to contrive optical systems atrespective portions of an image pickup apparatus such as a camera,thereby not only thinning a photographic system, a view finder system, alight measuring system, a range finding system at the respectiveportions but also enhancing performance of these systems.

[0013] In other words, it is necessary to configure the photographicsystem so as to exhibit predetermined performance of use even when anoptical path is bent, remove a moving space for diopter adjustment inthe view finder system, configure the light measuring system withoutcomplicating a mechanism so as to be capable of changing a focal lengthof a condense lens having a simple composition so as to make variable aweight coefficient distribution for the weighted mean light measurementaccording to a program of what portion of a photographic range of anobject is to be considered at what degree.

[0014] The light measuring system is configured so as to be capable ofchanging a focal length of a condenser lens system in order to change adistribution of weight coefficients in accordance with a magnificationchange of the photographic optical system.

[0015] Furthermore, it is necessary to configure the light measuringsystem so as to be capable of obtaining desired distributions of weightcoefficients from a wide position to a tele position in conjunction witha magnification change of a zoom lens system.

[0016] Furthermore, a light projector optical system of the rangefinding system is configured so as to have a simple composition withoutcomplicating a mechanism and be capable of changing a magnification ofthe light projector optical system in conjunction with a magnificationof the photographic optical system, and optimalizing a range findingregion from the wide position to the tele position.

[0017] Furthermore, it is necessary to obtain means for obtaining animage on which defocuses before and after a focus point are emphasizedby reducing an apparent depth of field of an image photographed with animage pickup apparatus which uses an image pickup device having a smalleffective image pickup surface size.

SUMMARY OF THE INVENTION

[0018] An object of the present invention is to provide an image pickupapparatus which comprises at least a view finder system, an automaticexposure control system, an automatic focusing mechanism and an opticalpath bending reflecting member which has an optical element having avariable shape included in optical systems comprised in these systems,and is configured to be capable of performing correction of an imagelocation, focusing and the like at a zooming stage by varying the shapeof a reflecting surface of the optical element having the variableshape.

[0019] Another object of the present invention is to provide an imagepickup apparatus comprising an optical system which comprises a firstlens unit disposed at a stationary location, comprising a negative lenselement and a positive lens element and having negative refractive powerand a second lens unit having positive refractive power, an optical pathbending reflecting surface having a variable shape disposed between amost object side lens component and a second lens unit of the first lensunit, and is configured to change mainly a magnification by moving onlythe second lens unit and correct a deviation of an image location duringa magnification change by varying the shape of the reflecting surface.

[0020] Another object of the present invention is to provide an imagepickup apparatus which comprises a first lens unit having positiverefractive power, a second lens unit having negative refractive powerand an optical path bending reflecting surface having a variable shapedisposed on the image side of a most image side lens component of thesecond lens unit, and is configured to change a magnification by movingthe second lens unit along an optical axis and correct a deviation of animage location by varying the shape of the reflecting surface during amagnification change.

[0021] Another object of the present invention is to provide an imagepickup apparatus which comprises a first lens unit having positive ornegative refractive power, a second lens unit having negative.refractive power, a third lens unit having positive refractive power andan optical path bending reflecting surface having a variable shapedisposed on the object side of a most object side lens component of thesecond lens unit, and is configured to change a magnification by movingat least the third lens unit and vary the shape of the reflectingsurface by moving the third lens unit for correcting a deviation of animage location during the magnification change.

[0022] Another object of the present invention is to provide an imagepickup apparatus comprising a photographic optical system and a viewfinder which comprises, in order from the object side along an opticalaxis, an objective lens system, an eyepiece system and image erectingreflecting mirrors, and is configured to form a real image between theobjective lens system and the view finder: one of the image erectingreflecting mirror having a variable shape.

[0023] Another object of the present invention is to provide an imagepickup apparatus comprising a photographic optical system and a lightmeasuring optical system for range finding which has a function todetermine an exposure time by measuring a light amount as a weightedmean of light amounts at location within a photographing range of anobject to be photographed with the photographic optical system.

[0024] Another object of the present invention is to provide an imagepickup apparatus comprising a photographic optical system, and a lightsource, a light projector optical system and a light measuring opticalsystem for range finding: the light projector optical system being anoptical system consisting of a light projector optical system and anoptical path bending reflecting optical element or an optical pathbending reflecting optical element and a light projector optical systemwhich are disposed in this order between the light source and an objectto be photographed by the photographic optical system, and thereflecting optical element being a reflecting optical element having avariable shape.

[0025] Still another object of the present invention is to provide animage pickup apparatus which comprises a photographic optical system, animage pickup device, an optical path bending reflecting optical elementhaving a variable shape disposed between an object and the image pickupdevice, and a control system for controlling a variation of the shape ofthe reflecting optical element.

[0026] A further object of the present invention is to provide an imagepickup apparatus comprising left and right photographic optical systemswhich are disposed side by side, and a plurality of reflecting opticalelements which are disposed on the object side of the photographicoptical systems respectively for giving parallax between left and rightsides.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIGS. 1 to 4 are sectional views showing photographic opticalsystems to be used in first to fourth embodiments of the image pickupapparatus of the present invention;

[0028]FIG. 5 is a diagram showing an example of a reflecting surface ofa variable shape optical element;

[0029]FIGS. 6A and 6B are diagrams showing a fifth embodiment of thepresent invention;

[0030]FIG. 7 is a diagram showing a sixth embodiment of the presentinvention;

[0031]FIGS. 8A and 8B are diagrams showing a seventh embodiment of thepresent invention;

[0032]FIG. 9 is a diagram showing an eighth embodiment of the presentinvention;

[0033]FIGS. 10A, 10B, 10C and 10D are curves visualizing an outline ofaberrations in an image pickup apparatus according to the eighthembodiment;

[0034]FIGS. 11A and 11B are diagrams showing a ninth embodiment of thepresent invention;

[0035]FIGS. 12A, 12B and 12C are diagrams showing a tenth embodiment ofthe present invention;

[0036]FIG. 13 is a diagram showing a configuration of a view finderaccording to an eleventh embodiment of the present invention;

[0037]FIGS. 14 and 15 are diagrams showing twelfth and thirteenthembodiments of the present invention;

[0038]FIGS. 16A, 16B and 16C are diagrams showing variations of a shapeof a reflecting optical element having a variable shape in an imagepickup apparatus according to the thirteenth embodiment;

[0039]FIGS. 17A, 17B and 17C are diagrams showing light amountdistributions in conditions shown in FIGS. 16A, 16B and 16Crespectively;

[0040]FIGS. 18A, 18B and 18C are diagrams showing variations of theshape of the reflecting optical element having the variable shape inzoom conditions of the image pickup apparatus according to thethirteenth embodiment;

[0041]FIGS. 19A, 19B and 19C are diagrams showing trimmed conditions ofan image pickup surface of the image pickup apparatus according to thethirteenth embodiment;

[0042]FIGS. 20A, 20B and 20C are diagrams showing shapes of thereflecting surface of the reflecting optical element having the variableshape corresponding to the trimmed conditions shown in FIGS. 19A, 19Band 19C;

[0043]FIGS. 21A, 21B, 21C and 21D are diagrams showing a fourteenthembodiment of the present invention;

[0044]FIGS. 22A, 22B and 22C are diagrams showing a fifteenth embodimentof the present invention;

[0045]FIG. 23 is a diagram showing a light projecting condition by alight projector optical system in the fifteenth embodiment of thepresent invention;

[0046]FIG. 24A, 24B and 24C are diagrams showing a sixteenth embodimentof the present invention;

[0047]FIG. 25 is a diagram descriptive of an image processing by theimage pickup apparatus according to the sixteenth embodiment of thepresent invention;

[0048]FIGS. 26A and 26B are diagrams showing a seventeenth embodiment ofthe present invention;

[0049]FIG. 27 is a diagram showing a configurational example ofreflecting optical element having a variable shape to be used by thepresent invention;

[0050]FIG. 28 is a diagram showing an example of electrode to be used inFIG. 27; and

[0051]FIG. 29 is a diagram showing another example of electrode to beused in FIG. 27.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] An image pickup apparatus which has a first composition accordingto the present invention comprises an optical system (photographic lenssystem) which comprises a first lens unit disposed at a fixed location,comprising at least a negative lens element and at least a positive lenselement and having negative refractive power, a second lens unit havingpositive refractive power, and an optical path bending reflectingsurface having a variable shape which is disposed between a most objectside lens component of the first lens unit and a most object side lenscomponent of the second lens unit, performs mainly a magnificationchange by moving only the second lens unit, and corrects a deviation ofan image location by varying the shape of the reflecting surface duringthe magnification change.

[0053] The optical system of the image pickup apparatus according to thepresent invention is configured on the basis of a typical typephotographic optical system for digital cameras, or a zoom type lenssystem which comprises a first lens unit having negative refractivepower and a composite system on and after a second lens unit havingpositive refractive power, comprises, in order from the object side, afirst lens unit disposed at a fixed location, comprising at least anegative lens element and at least a positive lens element and havingnegative refractive power, a second lens unit having positive refractivepower and an optical path bending reflecting surface having a variableshape disposed between a most object side lens component of the firstlens unit and a most object side lens component of the second lens unit,performs mainly a magnification changing function by moving only thesecond lens unit along an optical axis and corrects a deviation of animage location during a magnification change by varying the shape of thereflecting surface.

[0054] An ordinary zoom lens system which consists of a first lens unithaving negative refractive power and a rear lens group on and after asecond lens unit having positive refractive power as a whole moves thesecond lens unit on the object side to change a magnification from awide position to a tele position and corrects a deviation of a focalpoint location caused due to the magnification change by moving thefirst lens unit monotonously on the image side or while tracing a locusconvex on the image side.

[0055] The photographic optical system used in the image pickupapparatus according to the present invention is configured to use thefirst lens unit disposed at the fixed location, and adopts instead theoptical path bending reflecting surface having the variable shape and acontrol system which is capable of freely varying the shape of thereflecting surface, thereby correcting the deviation of the focal pointlocation (deviation of an image surface) caused during a magnificationchange. Furthermore, the photographic optical system is configured toperform also focusing by varying the shape of the reflecting surfacehaving the variable shape.

[0056] This reflecting surface (the optical path bending reflectingoptical element) consists, for example, of a thin film which has areflecting surface coated with a metal as described later, is connectedto a power source by way of a plurality of electrodes and variableresistors, and has an arithmetical unit for controlling resistancevalues of the variable resistors so that the shape of the reflectingsurface is varied by controlling a distribution of electrostatic forcesapplied to the thin film.

[0057] An optical system which corrects a focal point location byvarying a shape of a reflecting surface like the above described opticalsystem has a correcting capability lower than that of an optical systemwhich corrects a focal point location by mechanically moving a lensunit. It is therefore desirable to configure an optical system so as tohave a power distribution which shortens a moving distance required fora focal point location of a composite system of the first lens unititself and the reflecting optical element having the variable shape,that is, an object location of the composite system on and after thesecond lens unit so that a correction amount is as small as possible.

[0058] For this reason, it is desirable that the composite system on andafter the second lens unit has a magnification satisfying the followingcondition;

0.5<ABS(βW)<ABS(βT)<1.8

[0059] wherein reference symbols ABS(βW) and ABS(βT) representmagnifications of the composite system on and after the second lens unitat the wide position and the tele position respectively.

[0060] This condition utilizes a fact that a deviation of a focal pointlocation is generally small when magnifications of a composite system onand after a second lens unit are close to 1× at the wide position andthe tele position respectively. If an upper limit or a lower limit ofthis condition is exceeded, a focal point location will have a largecorrection amount and cannot be corrected sufficiently by varying ashape of a reflecting optical element having a variable shape.

[0061] An image pickup apparatus which has a second compositionaccording to the present invention adopts an optical system whichcomprises a first lens unit having positive refractive power, a secondlens unit having negative refractive power and an optical path bendingreflecting surface having a variable shape disposed on the image side ofa most image side lens component of the second lens unit, and isconfigured to perform a magnification change by moving the second lensunit along an optical axis and correct a deviation of an image locationduring the magnification change by varying the shape of the reflectingsurface.

[0062] The optical system of the image pickup apparatus which has thesecond composition is configured on the basis of a typical zoom typelens system for video cameras or one of types usable also for digitalcameras comprising a first positive lens unit, a second negative lensunit and a third positive lens unit and characterized by comprising, inorder from the object side, a first positive lens unit, a secondnegative lens unit and an optical path bending reflecting surface havinga variable shape disposed on the image side of a most image side lenscomponent of the second lens unit, performing a magnification change bymoving the second lens unit along an optical axis and correcting adeviation of an focal point location caused during the magnificationchange by varying the shape of the above described reflecting surface.In this case, a number of lens components and moving spaces on theobject side of a location of an optical path bent by the reflectingsurface makes it impossible to say that the composition exhibits asufficient effect for a thin configuration, but the composition makes itpossible to configure a reflecting surface on and after the second lensunit as a reflecting surface having a variable shape, correct adeviation of a focal point location caused during a magnification changeby varying the shape of the above described reflecting surface andperform controls such as focusing with the reflecting surface.

[0063] Furthermore, an image pickup apparatus which has a thirdcomposition according to the present invention uses an optical systemwhich is configured to comprise, in order from the object side, a firstlens unit having positive or negative refractive power, a second lensunit having negative refractive power, a third lens unit having positiverefractive power and an optical path bending reflecting surface having avariable shape disposed on the object side of a most object side lenscomponent of the second lens unit, and is configured to perform amagnification change by moving at least the third lens unit along anoptical axis and vary the shape of the reflecting surface having thevariable shape to correct a deviation of an image surface locationcaused during the magnification change.

[0064] The optical system used in the third composition is configured onthe basis of the typical type lens system for video cameras or anotherzoom type lens system usable for digital cameras consisting of a firstpositive or negative lens unit, a second negative lens unit, a thirdpositive lens unit and a fourth positive lens unit, comprises in orderfrom the object side the first positive or negative lens unit disposedat a fixed location, the second negative lens unit, the third positivelens unit and the optical path bending reflecting surface having thevariable shape disposed on the object side of the most object side lenscomponent of the second lens unit, performs the magnification change bymoving at least the third lens unit along the optical axis and correctsthe deviation of the focal point location caused during themagnification change by varying the shape of the reflecting surfacehaving the variable shape.

[0065] A zoom lens system which comprises a first lens unit havingpositive or negative refractive power, a second lens unit havingnegative refractive power and a third lens unit having positiverefractive power ordinarily moves the third lens unit on the image sideto change a magnification from a wide position to a tele position andcorrects a deviation of a focal point location causd during themagnification change by moving all or some of lens units disposed on theimage side of the third lens unit in a direction monotonously or whiletracing a locus convex on the object side or the image side.

[0066] For thinning an image pickup apparatus by bending an opticalpath, it is preferable to dispose an optical path bending reflectingsurface at any location between a most object side lens component of afirst lens unit and a most object side lens component of a second lensunit. In such a case, a space for disposing the optical path bendingelecting surface makes a moving space for the second lens unitinsufficient. A vari-focal ratio is lowered accordingly, but a controlsystem is disposed to permit freely varying a shape of the optical pathbending reflecting surface for making up for the lowered vari-focalratio and a variation of a focal length of a composite system of thefirst lens unit itself, a reflecting optical element having a variableshape and the second lens unit itself is corrected by varying the shapeof the reflecting surface.

[0067] Furthermore, it is also possible to bend an optical path bydisposing a reflecting optical element having a variable shape at anylocation in and after the second lens unit and correct a deviation of afocal point location caused during a magnification change by varying theshape of the reflecting optical element. In this case also, focusing maybe performed by varying the shape of the reflecting optical elementhaving the variable shape. In this case, it is adequate to vary theshape of the reflecting optical element in a direction perpendicular toa first bending direction.

[0068] In addition, the second lens unit may be fixed so far as a largevalue can be given to a variation of a focal length of the compositesystem of the first lens unit, the optical element having a variableshape and the second lens unit by imparting a vari-focal function tolens unit(s) disposed after the second lens unit and disposing areflecting optical element having a variable shape at any locationbetween the most object side lens component of the first lens unit andthe most object side lens component of the second lens unit.

[0069] For the optical system used in the image pickup apparatusaccording to the present invention described above, it is desirable thatthe control system for controlling the variation of the shape of thereflecting surface has additional functions described as the followingitems 1 to 7:

[0070] 1. The control system has not only a function for changing aparaxial amount but also a function for correcting aberrations byvarying the shape of the reflecting surface. For example, the controlsystem determines a paraxial amount by components of low orders of acurved surface and corrects aberrations by components of high orderslike a nature of an ordinary aspherical lens element whose paraxialamount is determined by a term of the second order of a formulaexpressing an aspherical surface and whose aberrations are corrected byterms of the fourth and higher orders.

[0071] 2. The control system for controlling the shape of the reflectingsurface has a function for control additionally with lens control datafor preventing vibration. That is, it is possible to prevent vibrationby varying a shape or an angle of a mirror surface instead of detectinga vibration amount of a lens system and mechanically correcting an imagelocation so as to be immovable on an image surface. In order words, itis possible to perform vibration prevention with quick response byapplying quick response of a mirror having a variable shape to avibration prevention function.

[0072] 3. The control system has a function for controlling the opticalsystem so as to follow positional shift of a main object (for example, acelestial body) with time lapse during long exposure so that an image isnearly immovable on an image surface.

[0073] 4. The control system has a function for controlling the opticalsystem so as to be focused on a best fit curved surface (on which a sumof squares of depths at points is minimum, for example) from multi-pointrange finding data. A typical example is swing photographing which iseffective for bringing the optical system into focus on an object whichis not located on a single plane.

[0074] 5. The control system has a function for controlling the opticalsystem so as to be capable of changing aberration conditions fordifferent modes such as a resolution emphasized mode, a distortion mode,a soft focus mode and the like. This function allows a user to selectaberration conditions at his will at a certain degree.

[0075] 6. The control system has a function for storing datacorresponding to shape variation amounts of a mirror which is to be usedfor changing a focal length in accordance with changes of specificationsfor CCDs and the like to be used and controlling the optical systemwhile considering the above described data in controlling a shape of amirror having a variable shape. Though a digital camera must be matchedwith specifications for a CCD, this function allows specifications to bevariable at a certain degree and to be modifiable including a size of aCCD.

[0076] 7. The control system has a function for storing a paraxialamount of a photographic lens system and result data of curvature offield into memory means and controlling a shape of a mirror having avariable shape while considering the above described result data. Thisfunction more or less moderates narrowing of an allowable variationrange of a result as picture elements are used in a larger number.

[0077] An image pickup apparatus which has a fourth compositionaccording to the present invention comprises a view finder in additionto a photographic optical system; the view finder being a view finder ofa type comprising, in order from the object side along an optical path,an objective lens system and an eyepiece system for forming a real imagebetween the objective lens system and the eyepiece system, that is, aKeplerian view finder, and configured to correct diopter by freelyvarying a shape of one of image erecting reflecting surfaces. Thoughdiopter can ordinarily be changed by moving all or some of lenscomponents of an eyepiece system, an image pickup apparatus is thickenedby moving spaces required of the lens components.

[0078] The view finder used in the image pickup apparatus according tothe present invention therefore uses an eyepiece system which is fixedand one of image erecting reflecting surfaces which is configured as areflecting optical element having a variable shape, and is configured tochange diopter by varying the shape of the reflecting optical element.This image pickup apparatus permits selecting diopter at a user's willand is capable of automatically correcting diopter using a range findingresult on a photographic system or zoom condition data.

[0079] When a photographic lens system has a high zoom ratio and acertain degree of magnification is reserved for a view finder at a wideposition, the view finder inevitably has a high magnification at a teleposition, whereby diopter is changed in too large an amount from aninfinite distance to an extremely short distance when peeped through theview finder at the tele position. Furthermore, diopter is apt to bedeviated largely at the wide position and the tele position.

[0080] It is sufficient for solving this problem to match diopter with amain object using a range finding result on a photographic lens systemor automatically correct diopter for each focal length using zoomcondition data. Though description has been made above of correction ofdiopter, it is possible to similarly correct parallax which is differentdependently on focal lengths and object distances.

[0081] An image pickup apparatus which has a fifth composition accordingto the present invention comprises a light measuring system forperforming range finding and the like which has a function for pickingup an image of an object as well as a function for determining anexposure time by measuring a light amount as a weighted mean of lightamounts at locations within a photographing range of an object at animage pickup stage and measures the light amount for the latterfunction. This light measuring system consists, in order from a side ofthe object, a condenser lens system, an optical path bending reflectingoptical element and a photosensor or an optical path bending reflectingoptical element, a condenser lens system and a photosensor. It isappropriate to configure an optical path bending reflecting opticalelement as a reflecting optical element having a variable shape, disposea control system capable of freely varying the shape of the reflectingoptical element in such a light measuring optical system so that adistribution of weight coefficients in a photographing range of anobject is variable and use the light measuring optical system in animage pickup apparatus.

[0082] The image pickup apparatus can be configured so as to be capableof performing two or more of a spot light measurement, a multi-spotlight measurement, center weighted light measurement and a pattern lightmeasurement.

[0083] Furthermore, it is preferable that an image pickup apparatuswhich has a photographic optical system consisting of a zoom lens systemis configured to comprise a control system which is capable of changinga light measuring range in conjunction with a change of a photographingrange. Furthermore, an image pickup apparatus may be configured to havea function for trimming and outputting an image pickup range, that is,the so called electronic zoom function. In this case, it is preferableto configure the image pickup apparatus so as to comprise a controlsystem which changes a light measuring range in conjunction with achange of a trimming range.

[0084] An optical path bending reflecting optical element consists of athin film which has a reflecting surface coated with a metal and isconnected to a power source by way of a plurality of electrodes andvariable resistors, has an arithmetic unit for controlling resistancevalues of the variable resistors and varies a shape of the reflectingsurface by controlling a distribution of electrostatic forces applied tothe this film.

[0085] An image pickup apparatus which has a sixth composition accordingto the present invention comprises a light projector optical system forrange finding, which is disposed separately from a photographic opticalsystem, has a function to pick up an image of an object and a rangefinding function at an image pickup time, or is an optical system whichconsists of the light projector optical system and an optical pathbending reflecting optical element or an optical path bending reflectingoptical element and a light projector optical system arranged in thisorder between a light source and the object: the optical path bendingreflecting optical element being a reflecting optical element having avariable shape and having a control system for controlling a shapevariation. This control system is capable of changing a light projectionrange or a light projection location on the object. In a case where animage pickup optical system of an image pickup apparatus is a zoom lenssystem in particular, it is possible to optimalize a light measuringregion from a wide position to a tele position by configuring the imagepickup apparatus so as to comprise a control system which is capable ofchanging a light projection range or a light projection location on anobject in conjunction with a change of a photographing range of the zoomlens system. When an image pickup system has the function for trimmingand outputting a photographing range (the so-called electronic zoomfunction), it is proper to configure the image pickup apparatus so as tocomprise a control system which is capable of changing a lightprojection range or a light projection location on an object.

[0086] An image pickup apparatus which has a seventh compositionaccording to the present invention comprises an imaging optical systemfor photographing and an image pickup device for photographing, areflecting optical element which bends an optical axis of the imagingoptical system ranging from an object through the imaging optical systemto the image pickup device and is configured as an optical elementhaving a variable shape and a control system for freely varying theshape of the reflecting optical element, is capable of releasing ashutter and picking up images a plurality of times within a short time,and has a control system which is capable of freely varying the shape ofthe reflecting optical element at a high speed in conjunction with ashift of a focal point location from the image pickup device at eachshutter release and makes it possible to photograph at a high speed aplurality of images of a nearly identical scene which have differentfocused points.

[0087] It is preferable to configure this image pickup apparatus so asto have a function which finally forms an image by composing theplurality of images of the nearly identical scene which have thedifferent focused points and a function permitting freely changing avignetted level dependently on a depth degree of the object so that theimage pickup apparatus is capable of outputting data of the composedimage. Moreover, the image pickup apparatus is applicable to animationsand monitoring as well as inspections with a magnifying optical systemhaving a shallow depth when the image pickup apparatus is configured tobe capable of performing real time processing for the functions.

[0088] An image pickup apparatus which has an eighth compositionaccording to the present invention is configured to be capable ofobtaining a stereoscopic image. In other words, the image pickupapparatus which has the eighth composition comprises two left and rightphotographic optical systems which are arranged side by side and aplurality of reflecting optical elements which are disposed on theobject side of the left and right photographic optical systemsrespectively for producing parallax between left and right sides, and isconfigured to image images of an identical object formed by the left andright photographic optical systems on a left half and a right half onthe image side of the photographic optical systems with slightlydifferent parallax between the left and right sides. Some of thereflecting optical elements disposed on the object side of the left andright photographic optical systems are configured to have reflectingsurfaces variable in shapes or the like. Accordingly, the image pickupapparatus is capable of obtaining a desired stereoscopic image bycontrolling the reflecting surfaces of the reflecting optical elementsvariable in the shapes or the like so as to vary the shapes, positionsor angles of the reflecting optical elements, thereby controlling avergence angle or a focus point.

[0089] The reflecting surface variable in shape (reflecting surface ofthe reflecting optical element having the variable shape) used in theimage pickup apparatus according to the present invention consists, forexample, of a thin film or the like having a reflecting surface coatedwith a metal as described later with reference to drawings, which isconnected to a power source by way of a plurality of electrodes andvariable resistors, and has an arithmetic unit for controlling values ofthe variable resistors so that the shape of the reflecting surface isvaried by controlling a distribution of electrostatic forces applied tothe thin film.

[0090]FIG. 1 shows a composition of a first embodiment of the imagepickup apparatus which has the first composition according to thepresent invention in a condition where the image pickup apparatus isfocused on an object located at an infinite distance.

[0091] As shown in FIG. 1, an optical system used in the image pickupapparatus according to the first embodiment comprises, in order from theobject side, a first lens unit G1 which consists of a negative lenselement LN1, a mirror VM having a variable shape, a negative lenselement LN2 and a positive lens element LP3 and has negative refractivepower as a whole, a stop S, a second lens unit G2 which consists of apositive lens element LP4 and a cemented lens component consisting of apositive lens element LP5 and a negative lens element LN6, is movedalong an optical axis for a magnification change and has positiverefractive power as a whole, a third lens unit G3 which consists of apositive lens element LP7, filters F which consists of an infrared cutfilter and a low pass filter, and a CCD. In addition, a reference symbolIS represents an image pickup surface of the CCD.

[0092] In other words, the optical system according to the firstembodiment is an optical system which comprises the first lens unit G1comprising two negative lens elements and a positive lens element, thesecond lens unit G2 having positive refractive power, the optical pathbending reflecting optical element VM having the variable shape disposedbetween an object side lens element LN1 which is an object side lenscomponent of the first lens unit and a lens element LP4 which is anobject side lens component of the second lens unit G2, changes amagnification by moving only the second lens unit G2 and is to be usedin the image pickup apparatus which has the first composition accordingto the present invention.

[0093] This optical system is configured to move the second lens unit G2along the optical axis for changing the magnification and vary the shapeof the variable shape mirror VM to change power of this mirror, therebycorrecting a deviation of a location of an image surface caused due tothe magnification change.

[0094] Furthermore, the optical system is focused on an object locatedat a short distance simply by varying the shape of the variable shapemirror VM.

[0095]FIG. 2 shows a photographic optical system used in a secondembodiment of the image pickup apparatus according to the presentinvention. The photographic optical system according to the secondembodiment comprises a first lens unit Gl consisting of a positive lenselement LP1, a second lens unit G2 consisting of a negative lens elementLN2 and a cemented lens component which consists of a negative lenselement LN3 and a positive lens element LP4 and has negative refractivepower, a mirror VM which is used for bending an optical path and has avariable shape, a third lens unit G3 consisting of a positive lenselement LP5, a cemented lens component which consists of a positive lenselement LP6 and a negative lens element LN7 and has negative refractivepower and a positive lens element LP8, filters F, and a CCD (only animage pickup surface IS is shown).

[0096] A photographic optical system according to the second embodimentcomprises the first lens unit G1 having positive refractive power, thesecond lens unit G2 having negative refractive power and the opticalpath bending reflecting optical element having a variable shape disposedon the image side of a negative lens element which is a most image sidelens component of the second lens unit G2, changes a magnification bymoving the second lens unit G2 and is to be used in the second ecomposition according to the present invention.

[0097] The second embodiment is configured to change a magnificationfrom a wide position W to a tele position T by moving the second lensunit G2 which is disposed on the object side of the optical path bendingmirror VM along the optical axis as indicated by an arrow, and correct adeviation of an image location caused during the magnification change byvarying a shape of the variable shape mirror VM. Furthermore, the secondembodiment is focused on an object located at a short distance simply byvarying the shape of the variable shape mirror.

[0098]FIG. 3 shows a third embodiment of the image pickup apparatusaccording to the present invention. As shown in this drawing, aphotographic optical system used in this image pickup apparatuscomprises a first lens unit G1 which consists of a positive lens elementLP1 and a negative lens element LN2, a variable shape mirror VM, asecond lens unit G2 which consists of a cemented lens componentconsisting of a negative lens element LN3 and a positive lens elementLP4, a stop S, a third lens unit G3 which consists of a positive lenselement LP5, and a cemented lens component consisting of a positive lenselement LP6 and a negative lens element LN7, a fourth lens unit G4 whichconsists of a positive lens element LP8, a filter F and a CCD (imagepickup surface IS).

[0099] The photographic optical system according to the third embodimentcomprises the first lens unit G1 having positive refractive power, thesecond lens unit G2 having negative refractive power and the third lensunit G3 having positive refractive power, changes a magnification bymoving at least the third lens unit G3, uses the optical path bendingreflecting optical element VM having the variable shape which isdisposed on the object side of a most object side lens element LN3 ofthe second lens unit G2 and is to be used in the image pickup apparatuswhich has the third composition according to the present invention.

[0100] The optical system according to the third embodiment changes amagnification from a wide position to a tele position by moving thethird lens unit G3 and the fourth lens unit G4 along an optical axis asindicated by an arrow in the drawing. During the magnification change,the optical system corrects a deviation of an image location by varyinga shape of the mirror VM having the variable shape and moving the secondlens unit G2 along the optical axis as indicated by an arrow (traced ina dashed line).

[0101] In addition, the second lens unit may be moved or fixed duringthe magnification change.

[0102]FIG. 4 is a sectional view illustrating a fourth embodiment of theimage pickup apparatus according to the present invention.

[0103] The fourth embodiment has a composition similar to that of thethird embodiment or is an image pickup apparatus comprising an opticalsystem which has the third composition according to the presentinvention, but is different from the third embodiment in that the fourthembodiment uses a mirror VM having a variable shape which is disposed ona most object side in the optical system.

[0104] In other words, a photographic optical system according to thefourth embodiment comprises, in order from the object side, a mirror VMhaving a variable shape, a first lens unit G1 which consists of apositive lens element LP1, a second lens unit G2 which consists of anegative lens element LN2 and a cemented lens component consisting of anegative lens element LN3 and a positive lens element LP4, a stop S, athird lens unit G3 which consists of a positive lens element LP5 and acemented lens-component consisting of a positive lens element LP6 and anegative lens element LN7, and a fourth lens unit G4 which consists of apositive lens element LP8, changes a magnification location by movingthe fourth lens unit or varying the shape of the mirror VM having thevariable shape.

[0105] It is possible for each of the image pickup apparatuses accordingto the first through fourth embodiments shown in FIGS. 1 through 4 notonly to change a paraxial amount such as surface power but also tocorrect aberrations by varying the shape of the mirror having thevariable shape. Furthermore, it is preferable to configure the mirror soas to have an aspherical surface within an effective surface of thereflecting surface. In a case where the reflecting surface has power inparticular, eccentric aberrations will be produced if the reflectingsurface has rotationally symmetric shape and a light bundle is incidenteccentrically on this reflecting surface. It is therefore preferable toconfigure the reflecting surface of the mirror having the variable shapeso as to have a curved surface which is not rotationally symmetric.

[0106] Furthermore, offaxial rays produce distortion which is notrotationally symmetric when a light bundle is incident eccentrically asdescribed above. In order to correct eccentric aberrations produced dueto eccentricity, the reflecting surface of the mirror having thevariable shape is configured as a curved surface which is symmetric withregard to only a plane including optical axes of rays incident andreflected onto and by the reflecting surface.

[0107]FIG. 5 is a diagram showing a form of the mirror VM having thevariable shape, which is symmetric with regard to a plane S(1, 2) whichincludes an optical axis 1 of a light bundle incident on the mirror VMhaving the variable shape and an optical axis 2 of the light bundlereflected by the mirror VM.

[0108] When the optical system is focused on an object located at aninfinite distance, the mirror having the variable shape has a planarsurface, but when the optical system is to be focused on an objectlocated at a short distance, the shape of the mirror is varied so as tobe an aspherical surface which is symmetric with regard to the planeS(1, 2) as shown in FIG. 5, thereby focusing the optical system on theobject located at the short distance and correcting the eccentricaberrations.

[0109] The mirror having the variable shape therefore makes it possiblenot only to configure an image pickup apparatus compact as a whole butalso allow the image pickup apparatus to correct aberrations and havefavorable optical performance.

[0110]FIGS. 6A and 6B are diagrams showing means for preventinginfluences due to vibrations such as hand vibrations.

[0111]FIG. 6A shows an image pickup apparatus free from band vibrations,whereas FIG. 6B shows an image pickup apparatus in a condition where ahand vibration correcting function is effective.

[0112] When an image pickup apparatus is turned downward and an opticalaxis direction 11 of a photographic optical system LS is turned downwardas shown in FIG. 6B, for example, from the condition free from thevibrations shown in FIG. 6A, a shape of the reflecting optical elementVM having the variable shape is varied so that reflected rays travel ina direction of an optical axis 2 and an optical axis of rays incident ona CCD or image pickup means 3 such as a film is not inclined. In thiscase, it is preferable not only to vary the shape of the reflectingelement VM having the variable shape for obtaining a function to preventthe optical axis from being inclined but also to correct the shape ofthe reflecting element VM having the variable shape as a whole so assuppress variations of aberrations.

[0113]FIG. 7 shows an example of image pickup apparatus which isconfigured to form an image always at an identical location on an imagesurface during exposure for a long time of a moving object such as acelestial body.

[0114] The image pickup apparatus is configured to vary a shape(curvature) of a variable shape mirror continuously as a moving objectST such as a celestial body moves from ST1 to ST2, thereby forming anobject such as a star always at an identical location on an imagesurface during exposure for a long time.

[0115]FIGS. 8A and 8B are diagrams showing an embodiment which performsrange finding to points at different object distances and is focused ona best fit curved surface (where a sum of squares of distances to thepoints is minimum, for example).

[0116] Shown in FIGS. 8A and 8B is an example in which a shape of amirror having a variable shape is varied so as to focus an photographicoptical system nearly on an object located at a distance C intermediatebetween a view at a long distance A and an object located at a shortdistance B.

[0117] In FIG. 8A, power to be applied to light bundles is varied on thebasis of an image formed by the view finder system dependently on theobjects at the distances A, B and C selected by a viewing ray inputdevice (not shown), and power applying portions of the mirror having thevariable shape are configured to be varied with signals from a CPU.

[0118]FIG. 9 shows a ninth embodiment of the image pickup apparatusaccording to the present invention. This embodiment is an image pickupapparatus which comprises an optical system using a mirror having avariable shape and is configured to allow selection among various modessuch as a normal photographic mode, a resolution emphasis mode, adistortion correcting mode and a soft focus mode.

[0119] An image pickup apparatus 10 has a dial 11 for selection amongthe above described modes and a shape of a mirror VM having a variableshape is varied into a shape in a mode directed by the dial 11 by way ofa CPU 12 as shown in FIG. 9.

[0120]FIGS. 10A, 10B, 10C and 10D show aberration conditions obtained byvarying a shape of a reflecting surface of the reflecting opticalelement VM having the variable shape in respective modes in the imagepickup apparatus shown in the above described FIG. 9. Out of thesedrawings, FIG. 10A is the normal mode, FIG. 10B is the resolutionemphasis mode, FIG. 10C is the distortion correcting mode and FIG. 10Dis the soft focus mode. As shown conceptionally in these drawings,spherical aberration, astigmatism and distortion are corrected with goodbalance in the normal mode shown in FIG. 10A, spherical aberration iscorrected favorably in particular in the resolution emphasis mode shownin FIG. 10B, distortion is corrected favorably in particular in thedistortion correcting mode shown in FIG. 10C and spherical aberration isproduced remarkably in the soft focus mode shown in FIG. 10D.

[0121] The image pickup apparatus having a composition shown in FIG. 9is configured to vary the shape of the reflecting optical element VMhaving the variable shape so as to obtain the above described aberrationconditions in an optical system and permit photographing desired images.

[0122]FIGS. 11A and 11B shows a tenth embodiment of the image pickupapparatus according to the present invention.

[0123] This embodiment is an example of image pickup apparatus which isconfigured so as to be capable of corresponding to image pickup devicesCCD(A) and CCD(B) which have different numbers of picture elements. Inother words, CCD(A) has a diagonal length of an image pickup surfacewhich is longer than that of CCD(B). The tenth embodiment permitsselection between the image pickup devices CCD(A) and CCD(B) to bedisposed on an image pickup surface of an image pickup optical system asdescribed above. However, a photographic field angle is changeddependently on the diagonal lengths of the image pickup surfaces whenthe image pickup devices are simply replaced with each other.

[0124] The image pickup apparatus according to the tenth embodimentreduces a difference between the field angles by varying a surface shapeof a reflecting optical element having a variable shape as indicated bya solid line and a dashed line as shown in FIG. 11B when the imagepickup device is replaced with the other. Specifically, the differencebetween variations of the field angles is reduced by varying the surfaceshape of the reflecting optical element having the variable shape so asto be a planar surface as shown as a variable shape reflecting opticalelement VM1 when CCD(A) is to be used or a convex surface as shown as avariable shape reflecting optical element VM2 when CCD(B) is to be used.

[0125]FIGS. 12A, 12B and 12C are diagrams showing an eleventh embodimentof the image pickup apparatus according to the present invention.

[0126] The eleventh embodiment is an example of image pickup apparatuswhich is configured to focus a photographic optical system by varying ashape of a reflecting optical element VM having a variable shape on thebasis of a signal obtained by a measurement with an automatic focusingmechanism.

[0127] An image pickup apparatus according to the eleventh embodiment isshown in FIG. 12A, in which a reference symbol LS represents an imagepickup optical system, a reference symbol VM designates a variable shapemirror, a reference numeral 15 denotes an automatic focusing mechanism,a reference numeral 16 represents a CPU and a reference numeral 17designates a memory. An optimum shape of the mirror having the variableshape is calculated by sending a signal obtained by a light measurementwith the automatic focusing mechanism to the CPU 16 as shown in FIG.12A, an object distance is calculated with this signal and calling outdata stored in the memory. A signal which controls the mirror VM havingthe variable shape so as to have the calculated shape is transmittedfrom the CPU 16, thereby varying a surface shape of the mirror VM havingthe variable shape and focusing the image pickup optical system.

[0128]FIGS. 12B and 12C show shapes of the reflecting optical element VMhaving the variable shape (FIG. 12B) and curvature of field(astigmatism) which correspond to distances to objects (FIG. 12C) whichare calculated on the basis of light measurements with the image pickupapparatus shown in FIG. 12A. In these drawings, a shape of a reflectingsurface and aberration conditions in a condition focused on an objectlocated at 50 cm are shown at an upper stage, a shape of the reflectingsurface and aberration conditions in a condition focused on an objectlocated at 1 m are shown at a middle stage, and a shape of thereflecting surface and aberration conditions in a condition focused onan object located at an infinite distance are shown at a lower stage.

[0129]FIG. 13 shows an embodiment comprising a Keplerian view finderwhich has the fourth composition according to the present invention oran example where one of image erecting reflecting surfaces is configuredas a variable shape mirror.

[0130] In FIG. 13, a reference numeral 21 represents an objective lenssystem which consists of a negative lens element and positive lenselements, a reference numeral 22 designates a visual field frame whichis disposed at a location of an intermediate image surface, a referencenumeral 23 denotes a roof prism, a reference numeral 24 represents apentagonal prism which has a convex surface of incidence 24 a and a roleof a condenser lens, and a reference numeral 25 designates an eyepieceoptical system consisting of an eyepiece.

[0131] In this embodiment, a surface 24 b which is a second reflectingsurface of the pentagonal prism 24 is configured as a mirror having avariable shape which is varied to adjust diopter for zooming,photographing an object located at a short distance, and correcting avergence angle between the prism 24 and a photographic lens system whichis not shown in FIG. 13. Furthermore, it is possible to vary the shapeof the surface for correcting a vergence angle so as to match with anear-sighted eye, a far sighted eye and an astigmatic eye of observers.

[0132] Furthermore, a view finder shown in the drawing is configured tochange a visual field for observation by moving a plurality of lenselements out of lens units (elements) composing the objective lenssystem 21.

[0133]FIG. 14 shows an embodiment of an image pickup apparatuscomprising a view finder having another composition in which a mirrorhaving a variable shape is used as a reflecting surface in a view finderwhich is similar to the view finder having the above describedcomposition.

[0134] In FIG. 14, a reference numeral 21 represents an objective lenssystem, reference symbols VM1 and VM2 designate mirrors having variableshapes respectively, a reference numeral 26 denotes a roof mirror and areference numeral 25 represents an eyepiece optical system; thesecomponents composing a view finder, for example, such as that shown inFIG. 13. Furthermore, the two mirrors VM1 and VM2 having the variableshapes are disposed in the view finder. Furthermore, a reference numeral15 represents an automatic focusing mechanism, a reference numeral 16designates a CPU, a reference symbol LS denotes a photographic lenssystem, for example, such as that shown in FIG. 1, 2, 3 or 4, areference numeral 27 represents a release button, a reference numeral 28designates a zoom switch, a reference numeral 29 denotes a drivingsystem for moving lens units for changing a magnification of thephotographic lens system (zoom lens system) LS and a reference numeral30 represents an image pickup device.

[0135] This image pickup apparatus performs a calculation with the CPU16 according to an instruction from the zoom switch 28, for example, andmoves the lens units of the photographic lens system along an opticalaxis with the driving system 29 so as to set a magnification at aninstructed level. Simultaneously, shapes of the mirrors having thevariable shapes are varied with a signal from the CPU 16 to correct adeviation of an image surface caused due to a magnification change whichis effected by moving the lens units with the driving system 29.

[0136] Furthermore, the objective lens system 21 of the view finderconsists, in order from the object side, of a negative lens unit, apositive lens unit and a positive lens unit, for example, as shown inFIG. 12A, and is configured to obtain a visual field for observationcorresponding to a photographing field angle by moving a plurality oflens units out of the three lens units. Furthermore, the mirror VM2 on aside of the eyepiece system 25 out of the variable shape mirrors VM1 andVM2 may be utilized for adjusting diopter so as to match it with diopterof an observer's eye.

[0137] Furthermore, the release button 27 inputs a signal from theautomatic focusing mechanism into the CPU 16, the CPU 16 calculates aphotographing object distance on the basis of this signal and calculateddata is sent to a mirror VM3 having a variable shape of the photographiclens system LS to vary a shape of a reflecting surface, therebyperforming focusing.

[0138] On the other hand, a view finder system is configured to vary ashape of the mirror VM1 having the variable shape on a side of theobjective lens system 21 in order to correct parallax between the viewfinder system and a photographing range on the basis of thephotographing object distance and a signal representing a zoom conditionof the photographic lens system. Simultaneously, the view finder systemvaries a shape of the mirror VM2 having the variable shape on a side ofthe eyepiece system so as to match diopter between a focused objectpoint and a visual field frame.

[0139] Out of the shapes of the three mirrors VM1, VM2 and VM3 havingthe variable shapes, those which are traced in solid lines are surfaceshapes in a condition where the photographic lens system is focused onan object located at an infinite distance, whereas those which aretraced in dashed lines designate surface shapes in a condition where thephotographic lens system is focused on an object located at a shortdistance.

[0140] The image pickup apparatus according to this embodiment iscapable of correcting parallax and diopter for the photographing rangeeasily as described above.

[0141]FIGS. 15, 16A, 16B, 16C, 17A, 17B, 17C, 18A, 18B, 18C, 19A, 19Band 19C show an embodiment of an image pickup apparatus which isconfigured to determine an exposure time at a stage to photograph anobject by measuring light amounts at locations within a photographingrange of the object and calculating a weighted mean.

[0142] In FIG. 15, a reference symbol LS represents a photographicoptical system, for example, such as that shown in any one of FIGS. 1 to4 which is a zoom lens system for forming an image on a light receivingsurface of image recording means such as an image pickup device, CCD ora film, and a signal indicating a zoom condition of the photographicoptical system is input into a CPU 16. Furthermore, a reference numeral31 designates a light measuring system which consists, in order from theobject aside, of a positive lens component L, a mirror VM having avariable shape and a light measuring element 32. Though the shown lightmeasuring element 32 has a single small light receiving surface, a lightmeasuring element may have a single light receiving surface or aplurality of light receiving surfaces which are patterned.

[0143] In an image pickup apparatus according to the embodiment shown inFIG. 15, rays which are incident on the positive lens component 1, andreflected by the mirror VM having the variable shape are measured by thelight measuring element 32 and measured data is input into the CPU 16.Furthermore, a reference numeral 33 represents a light measuring modeselecting mechanism which inputs a signal indicating a selected modeinto the CPU 16 upon selection of a specific mode. Furthermore, areference numeral 34 designates a trimming control mechanism which has afunction to permit modifying a photographing range when the imagerecording means 30 is an image pickup device or a visual field stop fordetermining an image pickup range is disposed right before an imagesurface when the image recording means 30 is a film surface.

[0144] In the image pickup apparatus according to this embodiment, theshape of the mirror VM having the variable shape of the light measuringsystem 31 which is disposed on a front surface of the apparatus isvaried into a surface shape calculated by the CPU 16 based on a zoomcondition of the photographic optical system LS and a light measuringmode selected by the light measuring mode selecting mechanism.

[0145] The above described light measuring mode is selectable, forexample, out of a center weighted light measurement, a center spot lightmeasurement mode and a center weighted mean light measurement mode.

[0146]FIGS. 16A, 16B, 16C, 17A, 17B and 17C variations of a surfaceshape (FIGS. 16A, 16B and 16C) and distribution of light amounts.(FIGS.17A, 17B and 17C) in the light measuring modes selected in the imagepickup apparatus shown in FIG. 15.

[0147]FIG. 16A shows a shape of the mirror VM having the variable shapewhen the center spot light measurement mode is selected by the lightmeasuring mode selecting mechanism 33 and a distribution of lightamounts in this mode is shown in FIG. 17A.

[0148] Furthermore, FIG. 16B shows a shape of the mirror VM having thevariable shape when the center spot measurement is selected and adistribution of light amounts in this mode is shown in FIG. 17B.

[0149] Furthermore, FIG. 16C shows a shape of the mirror having thevariable shape when the center weighted mean light measurement mode isselected and a distribution of light amounts in this mode is shown inFIG. 17C.

[0150] Furthermore, FIGS. 18A, 18B and 18C show operations for modifyinglight measuring ranges dependently on zoom conditions of an image pickupsystem (the photographic lens system): FIG. 18A showing a shape of areflecting surface at a wide position of the image pickup system, FIG.18B showing a shape of the reflecting surface at an intermediate focallength of the image pickup system and FIG. 18C showing a shape of thereflecting surface at a tele position of the image pickup system.

[0151] In the center weighted light measurement mode, the shape of thereflecting surface is convex in a zoom condition on a wide position sideof the intermediate focal length or concave in a zoom condition on atele position side of the intermediate focal length as shown in FIGS.18A, 18B and 18C. Accordingly, the image pickup apparatus is capable ofmodifying the light measuring range as a photographing range changes.

[0152]FIGS. 19A, 19B, 19C, 20A, 20B and 20C show operations formodifying the light measuring range dependently on image pickup surfacesand trimming conditions in the image pickup apparatus having thecomposition shown in FIG. 15. FIG. 19A shows a trimming condition in ahigh vision mode in which the photographing range is maximum, FIG. 19Bshows a trimming condition in a panoramic mode in which a vertical sizeis shortened and FIG. 19C shows a trimming condition in a classic modein which a horizontal size is shortened. FIGS. 20A, 20B and 20C showshapes of the mirror VM having the variable shape which are differentdependently on the modes shown in FIGS. 19A, 19B and 19C.

[0153] The mirror VM having the variable shape has a planar shape (basicshape) in the high vision mode as shown in FIG. 20A, a cylindrical shapeconvex in a vertical direction in the panoramic mode for shortening avertical size of the light measuring range as shown in FIG. 20B or acylindrical shape convex in a horizontal direction in the classic modefor shortening a horizontal size of the light measuring range. The imagepickup apparatus is capable of modifying the light measuring rangedependently on photographing conditions as described above.

[0154]FIGS. 21A, 21B, 21C and 21D show an embodiment in which a lightreceiving surface of a light measuring sensor SF has an area of acertain degree relative to an image pickup range. FIG. 21A shows acomposition of this embodiment in which mirrors VM1 and VM2 havingvariable shapes are disposed on both sides of a lens component L asshown in the drawing. FIG. 21B is a diagram showing a ray condensingcondition in the embodiment shown in FIG. 21A when it is configured tochange a degree of gradation on the light measuring sensor by changing asurface shape of the mirror VM2 having the variable shape on a side ofthe sensor. FIG. 21C shows a variation of a light measuring pattern inthe ray condensing condition shown in FIG. 21B and the embodiment iscapable of measuring light in various modes as shown in FIG. 21C.

[0155] Though a photographing range is changed by zooming a photographiclens system, the embodiment varies the shapes of the mirrors VM1 and VM2having the variable shapes of the light measuring system shown in FIG.21A, thereby being capable of changing an image magnification on thelight measuring sensor as shown in FIG. 21D without changing a lightmeasuring pattern and maintaining a light measurement mode desired by aphotographer.

[0156]FIGS. 22A, 22B and 22C show an embodiment of an image pickupapparatus which comprises a photographing system for picking up an imageof an object and a range finding system for measuring a distance at animage pickup stage.

[0157] In FIG. 22A, a reference symbol LS represents a zoom lens systemwhich is a photographic lens system, reference numerals 41 a, 41 b and41 c designate light emitting elements, a reference numeral 42 denotes alight projector lens component, a reference numeral 40 represents arange finding system consisting of a mirror having a variable shape orthe like, and a reference numeral 34 designates a trimming mechanism.

[0158] In this image pickup apparatus, information such as amagnification is sent from the photographic lens system LS to a CPU 16,information of the trimming mechanism 34 is input into the CPU 16 and ashape of the mirror VM having the variable shape is varied based on theinformation in the CPU 16. Accordingly, rays from the light emittingelements 41 a, 41 b and 41 c are projected through the light projectorlens component 42 to an object after the rays are reflected by themirror VM having the variable shape.

[0159]FIG. 22B shows a trimming condition and FIG. 22C shows a variationof a shape of the mirror VM having the variable shape in the trimmingcondition.

[0160] As shown in these drawings, the mirror VM having the variableshape has a planar surface shape for a usual screen size, whereas themirror VM having the variable shape has a convex cylindrical surfacehaving curvature in a vertical direction when a screen is trimmed asshown on a right side in FIG. 22B.

[0161]FIG. 23 shows an example where a light projecting range of thethree light sources 41 a, 41 b and 41 c is changed as the photographiclens system LS is zoomed in the image pickup apparatus shown in FIG.22A. In FIG. 23, a light projecting direction (direction toward anobject) is identical to that in FIG. 22A, and the light sources 41 a, 41b and 41 c are shown on a right side. Furthermore, the mirror VM havingthe variable shape is omitted in FIG. 23.

[0162] Rays from the three light sources are varied as shown in FIG. 23by varying the shape of the mirror VM having the variable shape, therebymaking it possible to change a photographing range at a wide positionfrom a photographing range at a tele position.

[0163]FIGS. 24A, 24B and 24C show an embodiment of an image pickupapparatus which is capable of picking up at a high speed a plurality ofimages which have different focused locations.

[0164]FIGS. 24A and 24 show a configuration of the above described imagepickup apparatus, which consists of a photographic lens system LS, amirror VM having a variable shape, an image sensor 45, a memory 46, animage processing device 47 and the like.

[0165] This image pickup apparatus is configured to keep stationary arefractive optical element of the photographic lens system LS and varythe shape of the mirror VM having the variable shape in the lens systemat a high speed in response to shutter release so as to focus the lenssystem on a plurality of points. Furthermore, the image sensor 45 whichis a CCD or the like records images of the points in focused conditionsand inputs the images into the memory 46. Based on the images stored inthe memory 46, the image pickup apparatus is capable of performing aprocessing to compose an image having an optional apparent depth withthe image processing device 47.

[0166] Furthermore, the fixed lens system LS shown in FIG. 24B may bereplaced with a movable lens system as shown in FIG. 24C when the imagepickup apparatus is to pickup only an image.

[0167]FIG. 25 shows an image processing by the image pickup apparatuswhich has the configuration shown in FIG. 24A. FIG. 25 shows an exampleto process three images: 50 a at a short distance, 50 b at anintermediate distance and 50 c at a far distance. On these images 50 a,50 b and 50 c, solid lines represent sharply focused portions, chainlines designate slightly defocused portions and dashed lines denotevignetted portions.

[0168] Signals of these images 50 a, 50 b and 50 c are input into theimage processing device 47 for image processing.

[0169] By this image processing, the image pickup apparatus is capableof outputting an image 51 a having a pan-focus effect, an image 51 bhaving a vignetted effect and an image 51 c in soft focus.

[0170] By extracting and composing only portions having high contrastfrom the images 50 a, 50 b and 50 c, the image pickup apparatus iscapable of providing a clear image like the image 51 a shown as aconceptional image which is in good focus from a near scene to a farscene. In other words, the image pickup apparatus is capable ofproviding an image which has the pan focus effect.

[0171] In other to obtain an image having the above described effect byordinary photographing, it is necessary to expose a film for a long timein a stop down condition, but an image may be blurred when an objectmoves.

[0172] In contrast, the image pickup apparatus according to thisembodiment does not require stopping down and is therefore capable ofproviding an image in pan focus through the image processing even theimage pickup apparatus is held by hand during photographing.

[0173] Furthermore, it is possible to obtain an image having such avignetted effect as to emboss a main object by adopting a main object infocus and most vignetted images before and after the main objects fromthe above described images 51 a, 51 b and 51 c. This vignetted effect isconvenient for emphasizing a main object as in photographing a person orthe like.

[0174] For a digital camera or a video camera which uses an imagesensor, there lies a limit in shallowing a depth of field forconfiguring an image sensor an optical system compact. An imageprocessing such as that by the image pickup apparatus shown in FIGS.24A, 24B and 24C makes it possible to compose an image having a depth offield shallower than one beyond performance of a camera.

[0175] Furthermore, the image pickup apparatus is capable of providingan image like the image 51 c which has a soft focus effect giving a softimpression like the image 51 c by adopting portions in focus andvignetted portions at the same time to compose an image.

[0176]FIGS. 26A and 26B show an embodiment of an image pickup apparatuswhich is configured for obtaining a stereoscopically observable image byforming images of an identical object on a left half and a right half ofan image pickup surface with slight parallax, and uses mirrors havingvariable shapes as some of a plurality of reflecting optical elementsdisposed on the object side of a photographic optical system for givingparallax between the left and right side images: FIG. 26A being aconfigurational diagram and FIG. 26B being a perspective view.

[0177] In FIGS. 26A and 26B, a reference numeral 60 represents a mainlens system, a reference numeral 61 designates image pickup means suchas an image pickup device like a CCD in a film surface, referencenumerals 62 a, 63 a, 62 b and 63 b denote left and right reflectingoptical elements, out of which 62 a and 63 a are the mirrors having thevariable shapes.

[0178] This image pickup apparatus forms a stereoscopically observableimage by reflecting left and right light bundles which are incident withslight parallax using the reflecting optical elements 62 a, 63 a, 62 band 63 b respectively, and imaging the light bundles onto the left halfand right half respectively of the image pickup means 61 using the mainlens system 60.

[0179] This image pickup apparatus can be focused from an object locatedat an infinite distance onto an object located at a short distance byvarying shapes of the left and right mirrors 62 a and 63 a having thevariable shapes from shapes traced in solid lines to shapes traced indashed lines.

[0180] An examples of a mirror having a variable shape (reflectingoptical element having a variable shape) to be used in the image pickupapparatus according to the present invention will be described below.

[0181]FIG. 27 shows a mirror 70 having a variable shape consisting of apiezoelectric element 70 disposed between a thin film 70 a andelectrodes 70 b which are disposed on a supporting base 71. Voltageswhich are to be applied to the piezoelectric element 70 c are changeddependently on the electrodes 70 b so as to cause different localelongations and contractions of the piezoelectric element 70 c, therebyvarying a shape of the thin film 70 a. The electrode 70 b may have ashape concentrically divided as shown in FIG. 28, rectangularly dividedas shown in FIG. 29 or another adequately selectable shape. In thedrawings, a reference numeral 72 blur sensor which is connected to anarithmetic unit 73 for detecting, for example, blur of a digital cameraand changing voltages to be applied to the electrodes 70 b by way of thearithmetic unit 73 and variable resistors 74 so that the shape of thethin film 70 a is varied so as to compensate for image disturbance dueto the blur. At this stage, focusing, temperature compensation and thelike are also performed while simultaneously taking into considerationsignals from a temperature sensor 75, a humidity sensor 76 and adistance sensor 77. In this case, it is preferable to configure the thinfilm 70 a so as to have a thickness at a certain degree since a stressproduced due to the variation of the shape of the piezoelectric element70 c is also applied to the thin film 70 a.

1. An image pickup apparatus comprising: an image pickup optical systemwhich comprises, in order from the object side, a first lens unitdisposed at a fixed location, comprising at least a negative lenselement and at least a positive lens element and has negative refractivepower, a second lens unit having positive refractive power, and anoptical path bending reflecting optical element having a variable shapedisposed between a most object side lens component of said first lensunit and a most object side lens component of said second lens unit, andis configured to change a magnification by moving only said second lensunit along an optical axis.
 2. An image pickup apparatus comprising: animage pickup optical system which comprises, in order from the objectside, first lens unit having positive refractive power, a second lensunit having negative refractive power and an optical path bendingreflecting surface having a variable shape disposed on the image side ofa most image side lens component of said second lens unit, and isconfigured to change a magnification by moving said second lens unitalong an optical axis.
 3. An image pickup apparatus comprising: an imagepickup optical system which comprises, in order from the object side, afirst lens unit having positive or negative refractive power, a secondlens unit having negative refractive power, a third lens unit havingpositive refractive power and an optical path bending reflecting surfacehaving a variable shape disposed on the object side of a most objectside lens component of said second lens unit, and is configured tochange a magnification by moving at least said third lens unit along anoptical axis.
 4. An image pickup apparatus comprising: an image pickupoptical system and a view finder, wherein said view finder comprises anobjective lens system, an eyepiece system and image erecting reflectingsurfaces, wherein said view finder forms an intermediate image betweensaid objective lens system and said eyepiece system, wherein one of saidimage erecting reflecting surfaces has a variable shape, and whereinsaid image pickup apparatus is configured to correct diopter of saidview finder by varying the shape of said reflecting surface having thevariable shape.
 5. An image pickup apparatus comprising: an image pickupoptical system which forms an image of an object; and a light measuringoptical system which determines an exposure time by measuring a lightamount as a weighted mean of light amounts at a plurality of locationswithin a photographing range of the object at a photographing time anddetecting an exposure time, wherein said light measuring optical systemcomprises, in order from the object side, a condenser lens system, anoptical path bending reflecting optical element and a condenser lenscomponent or an optical path bending reflecting element, a condenserlens component and a photosensor, wherein said reflecting opticalelement is a reflecting optical element having a variable shape, andwherein said light measuring optical system has a control system forvarying the shape of said reflecting optical element.
 6. An image pickupapparatus comprising: an image pickup optical system which picks up animage of an object; and a light projector optical system which isdisposed separately from said image pickup optical system and projectsrays to be used for range finding, wherein said light projector opticalsystem has a light source and comprises, in order from said lightsource, a projector lens component and an optical path bendingreflecting optical element or an optical path bending reflecting opticalelement and a projector lens component between said light source andsaid object, and wherein said optical path bending reflecting opticalelement is an optical element having a variable shape and said imagepickup apparatus has a control system for varying a reflecting surfaceof said optical element having the variable shape.
 7. An image pickupapparatus comprising: an image pickup optical system; an image pickupdevice; and an optical path bending reflecting optical element which isdisposed in a section from an object through said image pickup opticalsystem to said image pickup device, wherein a reflecting surface of saidreflecting optical element has a variable shape, and wherein the imagepickup apparatus has a control system which varies the shape of thereflecting surface, is capable of performing shutter release and imagepickup a plurality of times within a definite time, and picks up aplurality of images of a nearly identical scene which are focused atdifferent locations by automatically varying the shape of the reflectingsurface of said reflecting optical element so as to move a focusedlocation relative to said image pickup device at each shutter release.8. An image pickup apparatus comprising: left and right image pickupoptical systems; and an image pickup device, wherein each of said leftand right image pickup optical systems has a plurality of reflectingoptical elements disposed on the object side for giving parallax betweenleft and right sides, wherein said left and right image pickup opticalsystems form images with slight parallax on left side and right sidesrespectively on an image pickup surface of said image pickup device,wherein at least some of said reflecting optical elements of said leftand right image pickup optical systems are configured to have reflectingsurfaces having variable shapes, and wherein the image pickup apparatushas a control system which controls a vergence angle or a focus point byfreely varying the shape, locations and angles of said reflectingoptical elements having the reflecting surfaces having the variableshapes.
 9. The image pickup apparatus according to claim 1, wherein aparaxial amount of said image pickup optical system is changed andaberrations are corrected by varying a surface shape of said reflectingoptical element having the variable shape.
 10. The image pickupapparatus according to claim 1, wherein a surface shape of saidreflecting optical element having the variable shape is varied on thebasis of lens control data for reducing an influence due to vibrations.11. The image pickup apparatus according to claim 1, configured tocontrol the shape of said reflecting optical element having the variableshape so that an image of a main object is nearly immovable on an imagesurface during exposure for a long time.
 12. The image pickup apparatusaccording to claim 1, further comprising a multi-point range findingmechanism, wherein the shape of said reflecting optical element havingthe variable shape is varied so that the image pickup optical system isbrought into focus on each point using data provided from saidmulti-point range finding mechanism.
 13. The image pickup apparatusaccording to claim 1, wherein a surface shape of said reflecting opticalelement having the variable shape is varied so as to obtain optionalaberration conditions in said image pickup optical system.
 14. The imagepickup apparatus according to claim 1, comprising an image pickupdevice, wherein a surface shape of said reflecting optical elementhaving the variable shape is varied so as to changes a focal length ofsaid image pickup lens system in correspondence to a change of saidimage pickup device.
 15. The image pickup apparatus according to claim1, configured to control a surface shape of said reflecting opticalelement having the variable shape taking into consideration data of aparaxial amount or curvature of field in said image pickup opticalsystem.
 16. The image pickup apparatus according to claim 15,comprising: a view finder which automatically adjusts diopter by varyingthe surface shape of said reflecting optical element having the variableshape on the basis of data of a focused condition or a zoom condition ofsaid image pickup optical system.
 17. The image pickup apparatusaccording to claim 15, configured to vary the surface shape of saidoptical system having the variable shape on the basis of data of afocused condition or a zoom condition of said image pickup opticalsystem.
 18. The image pickup apparatus according to claim 15, configuredto be capable of performing two or more of a spot light measurement, amulti-spot light measurement, a center weighted light measurement andcenter weighted mean light measurement and a pattern light measurement.19. The image pickup apparatus according to claim 5, wherein said imagepickup optical system is a zoom lens system and wherein the image pickupapparatus comprises a control system which changes a light measuringrange in conjunction with a change of an image pickup range caused by amagnification change of the zoom lens system.
 20. The image pickupapparatus according to claim 5, comprising: a function to trim andoutput an image pickup range of said image pickup optical system; and acontrol system which is capable of changing a light measuring range inconjunction with a change of a trimming range.
 21. The image pickupapparatus according to claim 6, wherein said image pickup optical systemis a zoom lens system and wherein the image pickup apparatus comprises acontrol system which changes a light projection range or a lightprojection location of said light projector optical system inconjunction with a change of an image pickup range causes by amagnification change of this zoom lens system.
 22. The image pickupapparatus according to claim 6, comprising: a function to trim andoutput an image pickup range of said image pickup optical system; and acontrol system which changes a light projection range of said lightprojector optical system to an object or a light projector unit inconjunction with a change of a trimming range.
 23. The image pickupapparatus according to claim 7, comprising: a function to compose aplurality of images of a nearly identical scene having different focusedlocations into a single image; and a function which is capable ofchanging a vignetted degree associated with a depth of an object,wherein the image pickup apparatus is capable of outputting data of acomposed image.
 24. The image pickup apparatus according to claim 23,having an animation mode.
 25. The image pickup apparatus according toclaim 7, having an animation mode.
 26. The image pickup apparatusaccording to claim 5, wherein said reflecting optical element having thevariable shape has a reflecting surface consisting of a thin film coatedwith a metal and electrodes connected to a power source by way ofvariable resistors, wherein the image pickup apparatus further comprisesan arithmetic unit which controls resistance values of said variableresistors and wherein the image pickup apparatus controls a distributionof electrostatic forces to be applied to said thin film with saidarithmetic unit, thereby varying the reflecting surface of said variableshape reflecting optical element having the variable shape.
 27. Theimage pickup apparatus according to claim 7 which controls the surfaceshape of the reflecting surface of said reflecting optical elementhaving the variable shape in picking up a plurality of images of saidnearly identical scene having different focused locations at a highspeed.